Departing from his written text for a moment in his meeting with Harlem schoolchildren Friday afternoon, Pope Francis turned to one of his favorite topics, telling the students and their teachers that the devil is a killjoy who tries to spoil our dreams and destroy our happiness.

The Pope encouraged the children to live with joy in their hearts. “I see you smiling. Keep living like this,” the Pope said. “Help others to experience joy. It’s not easy. In every home there are problems, difficult situations, sickness. But don’t stop dreaming of living with joy.”

“All of you here, young and old, have the right to dream,” he continued, expressing his gladness that the school provides an atmosphere that supports them. “Where there are dreams, where there is joy, Jesus is always present. Always,” he said.

“On the other hand,” Francis asked the children, “who is the one who sows sadness, who sows distrust, who sows envy, who sows evil desires? What is his name?”

At this, some of the children answered quietly, and the Pope nodded.

“The devil, the devil!” he exclaimed. “The devil always sows sadness because he doesn’t want us happy. He doesn’t want us to dream.”

“Where there is joy, Jesus is always present,” Francis said. “Because Jesus is joy, and he wants to help us so that his joy stays with us every day.”

Friday’s off-the-cuff remarks were not the first time the Pope has encouraged Christians to believe in the existence of the devil and to resist his temptations.

Last October, in one of his homilies at morning Mass, Francis said that the devil “is not a myth” and that “we have to fight him.”

This generation, the Pope said, “was led to believe that the devil was a myth, a picture, an idea, the idea of evil. But the devil exists, and we have to fight him. These are Saint Paul’s words, not mine!”

“The devil,” the Pope went on, “is a liar, the father of lies.”

The Pope has similarly praised the work of exorcists, priests dedicated to the work of deliverance and casting out demons.

Without faith, there is no going forward, Francis said. “We need this shield of faith” because “the devil doesn’t throw flowers at us” but “flaming arrows” to kill us, he said.